Alterations of the gamma-carboxyglutamic acid and osteocalcin concentrations in vitamin D-deficient chick bone.
The content of osteocalcin and protein bound gamma-carboxyglutamic acid (Gla) was studied as a function of bone maturation and mineralization in normal and vitamin D-deficient, rachitic chickens. The Gla/Ca2+ ratio was elevated in rachitic bone, particularly in the most undermineralized regions. For example, there is a 10- to 20-fold elevation in Gla/Ca2+ in the newly synthesized, least mineralized rachitic bone fraction, which progressively decreases to a 1.5-fold elevation in the most highly mineralized areas of rachitic tissue. Osteocalcin, which is the principal Gla-containing protein of mature bone, was quantitated by radioimmunoassay using specific antiserum to the 5670-dalton chicken protein. Surprisingly, the osteocalcin concentration is decreased 50% in vitamin D-deficient bone. From this we infer that accumulated Gla-containing protein in vitamin D-deficient and poorly mineralized bone may possibly represent a precursor of osteocalcin.
D015055:1-Carboxyglutamic Acid / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002645:Chickens; D004492:Edetic Acid; D005971:Glutamates / Q000378:metabolism*; D008297:Male; D015675:Osteocalcin; D014808:Vitamin D Deficiency / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D005971:Glutamates; D015675:Osteocalcin; D015055:1-Carboxyglutamic Acid; D004492:Edetic Acid; D002118:Calcium